tbuckley/cabot-search huggingface dataset:
Abstract B065: Polymerase theta inhibition activates the cGAS-STING signaling pathway and elicits an immune response in homologous recombination-deficient pancreatic adenocarcinoma
Authors: Grace Oh, Annie Wang, Lidong Wang, Jiufeng Li, Gregor Werba, Daniel Weissinger, Ende Zhao, Surajit Dhara, Rosmel Hernandez, Amanda Ackermann, Despoina Kalfakakou, Emily A. Kawaler, Talia Golan, Theodore H. Welling, Agnel Sfeir, Diane M. Simeone
Journal: Cancer Research (2022)

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy that harbors mutations in homologous recombination (HR) repair genes in up to 25% of cases. Defects in HR impart to tumor cells a specific vulnerability to poly-ADP ribose polymerase inhibitors and platinum-based chemotherapy. However, not all patients respond, and some who initially respond develop resistance and progress. Thus, new therapies that are effective against HR-deficient PDAC are needed. Here, we show that inactivation of the HR pathway in PDAC is associated with overexpression of polymerase theta (Polθ, or POLQ), a key enzyme that regulates the alternative non-homologous end-joining (alt-NHEJ) pathway of double-strand break (DSB) DNA repair. Using both human and murine HR-deficient PDAC models, we find that POLQ knockdown is synthetically lethal with mutations in HR genes (BRCA1, BRCA2, and PALB2) as well as the DNA damage repair gene ATM. Further, we present the first findings that POLQ knockdown enhances cytosolic micronucleus formation and activates cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling. In an in vivo murine model, POLQ inhibition also leads to STING-dependent recruitment of immune cells and enhanced CD8+ T cell infiltration in the BRCA2-deficient tumor microenvironment (TME). Through its role in the alt-NHEJ pathway, we thus find that POLQ is critical for DSB repair in HR-deficient PDAC, and its inhibition presents a novel synthetic lethal approach to suppress tumor growth while simultaneously stimulating an immune response in the PDAC TME. Citation Format: Grace Oh, Annie Wang, Lidong Wang, Jiufeng Li, Gregor Werba, Daniel Weissinger, Ende Zhao, Surajit Dhara, Rosmel Hernandez, Amanda Ackermann, Despoina Kalfakakou, Emily A. Kawaler, Talia Golan, Theodore H. Welling, Agnel Sfeir, Diane M. Simeone. Polymerase theta inhibition activates the cGAS-STING signaling pathway and elicits an immune response in homologous recombination-deficient pancreatic adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B065.
Abstract B079: Unfolding the role of cell state on stress granule heterogeneity and function in pancreatic cancer
Authors: Alexandra Redding, Guillaume Fonteneau, Elda Grabocka
Journal: Cancer Research (2022)

Abstract Phenotypic and functional heterogeneity is a common feature of cancer cells that poses as a major therapeutic challenge. Previous work has implicated the phase-separation organelles, stress granules (SGs), as important mediators of tumorigenesis that function as a mutant KRAS-driven stress-adaptive mechanism to enhance cellular fitness. We have found that mutant KRAS pancreatic cancer cells show a high degree of intra-cellular heterogeneity in SG formation, ranging from no SGs to markedly high levels. Given the function of SGs in cancer cell fitness and the role of cancer cell heterogeneity in tumor progression and therapeutic response, we sought to understand the determinants of SG heterogeneity and its role in KRAS-driven tumorigenesis. Here, we show that the capability of KRAS mutant pancreatic cancer cells to form SGs is dependent on the cell cycle state, with cells in G2 phase showing markedly enhanced SG formation. We demonstrate that this heterogeneity in SG formation is determined by a cell cycle specific interplay between the activator of cell death, Caspase 3, and the SG regulator molecule 15-deoxy-delta-12,14-prostaglandin J2 (15-d-PGJ2). We show that 15-d-PGJ2 production in G2 is driven by calcium-dependent phospholipase A2 (cPLA2) activity and is subject to regulation by Caspase 3. Our results show that the capacity of Caspase 3 to cleave and inactivate the cPLA2 protein is specifically suppressed in G2, thus leading to upregulation of cPLA2 activity and 15-d-PGJ2 levels. As such, we find that 15d-PGJ2 levels are highest in G2 and that the inhibition of cPLA2 blocks SG formation in G2 specifically. Accordingly, exogenous 15d-PGJ2 rescues SG formation in cPLA2-inhibited G2 cells. In addition, we demonstrate that Caspase 3 inhibition increases 15-d-PGJ2 levels and stimulates SG formation in asynchronous cells, mirroring the natural suppression of Caspase 3 seen in G2. Importantly, we show that heterogeneity in SG levels translates into a functional heterogeneity whereby SG inhibition preferentially sensitizes cells in G2 to stress stimuli. Altogether these data support a model whereby SG formation integrates cues from cell death and proliferative signals and indicate that SG levels may be critical to achieve a clear signal for cell cycle progression at the G2/M border. Furthermore, our findings suggest that cancer cells may show differential sensitivity to anti-SG therapy as they progress through the cell cycle, and pairing such therapy with G2-synchronizing chemotherapeutics may increase susceptibility and thus treatment efficacy. Citation Format: Alexandra Redding, Guillaume Fonteneau, Elda Grabocka. Unfolding the role of cell state on stress granule heterogeneity and function in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B079.
Abstract A057: Therapeutic efficacy of selective CDK7 inhibition in pancreatic cancer mediated by induction of R-loop formation, DNA replication stress and genomic instability
Authors: Annan Yang, Jie Jiang, Ziyue Li, Kevin S. Kapner, Hanrong Feng, Kristen E. Lowder, Miljan Kuljanin, Whiteny Johnson, Giselle Uribe, Jasper E. Neggers, Shengwu Liu, Tinghu Zhang, James Decaprio, Ewa Sicinska, Brian M. Wolpin, Nicholas P. Kwiatkowski, Stephanie K. Dougan, Joseph D. Mancias, Nathanael S. Gray, Andrew J. Aguirre
Journal: Cancer Research (2022)

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a devastating cancer with 5-year overall survival of less than 10% and few effective therapies. Here, we demonstrate that cyclin dependent kinase 7 (CDK7) is essential for the proliferation and viability of PDAC cells by showing potent anti-tumor efficacy for the CDK7-specific inhibitor YKL-5-124 in preclinical PDAC models. Selective CDK7 inhibition leads to G2/M cell cycle arrest and apoptosis in PDAC, while mediating a more modest transcriptional response compared with multi-targeted CDK7 inhibitors. YKL-5-124 treatment impairs DNA damage repair pathways in PDAC cells and evokes genomic instability by inducing R-loop formation and DNA replication stress in telomeric regions leading to chromosomal bridging and micronuclei formation. Furthermore, we demonstrate that selective CDK7 inhibition has in vitro and in vivo combinatorial efficacy with gemcitabine chemotherapy through pronounced induction of replication stress and apoptosis. Collectively, these findings support selective CDK7 inhibition as a promising therapeutic strategy for PDAC. Citation Format: Annan Yang, Jie Jiang, Ziyue Li, Kevin S. Kapner, Hanrong Feng, Kristen E. Lowder, Miljan Kuljanin, Whiteny Johnson, Giselle Uribe, Jasper E. Neggers, Shengwu Liu, Tinghu Zhang, James Decaprio, Ewa Sicinska, Brian M. Wolpin, Nicholas P. Kwiatkowski, Stephanie K. Dougan, Joseph D. Mancias, Nathanael S. Gray, Andrew J. Aguirre. Therapeutic efficacy of selective CDK7 inhibition in pancreatic cancer mediated by induction of R-loop formation, DNA replication stress and genomic instability [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A057.
Abstract C039: An EGFR-activated subset of myofibroblastic cancer-associated fibroblasts supports local metastatic dissemination in pancreatic ductal adenocarcinoma
Authors: Gianluca Mucciolo, Joaquín Araos Henríquez, Sara Pinto Teles, Judhell Manansala, Wenlong Li, Eloise G. Lloyd, Priscilla Cheng, Giulia Biffi
Journal: Cancer Research (2022)

Abstract Pancreatic ductal adenocarcinoma (PDA) has a dismal prognosis and new therapies are needed. Cancer-associated fibroblasts (CAFs) can promote PDA progression and are recognized promising therapeutic targets. However, the ongoing characterization of PDA CAF heterogeneity and plasticity and the identification of potential tumor-restraining CAF populations have highlighted the need to further dissect the diverse biology of PDA CAFs to develop effective combination therapies. Using pancreatic organoid/fibroblast co-cultures and organoid-derived transplantation mouse models of PDA, we mechanistically investigated the signaling cascade downstream TGF-beta activation, which is a main driver of myofibroblastic CAF (myCAF) formation. We find that the EGFR/ERBB2 pathway is activated by TGF-beta in a subset of myCAFs, in both murine and human PDA, via amphiregulin induction and autocrine signaling. ERBB activation is important for the maintenance of this myCAF subset, with genetic and pharmacological inhibition of this pathway differentially affecting PDA CAF composition both in culture and mouse models. Importantly, analysis of lung cancer and breast cancer patient samples suggests that our observations in PDA are also relevant to these malignancies. Finally, we reveal a role of this EGFR-activated myCAF subset in promoting local metastatic dissemination in PDA and indicate new potential combination strategies. Our study highlights the need to better dissect PDA CAF heterogeneity also in populations typically considered to be tumor-restraining, in order to develop effective combination strategies for future clinical intervention. Our work also reveals how cancer-targeting therapies can directly affect the surrounding microenvironment with potential clinical implications for various malignancies. Citation Format: Gianluca Mucciolo, Joaquín Araos Henríquez, Sara Pinto Teles, Judhell Manansala, Wenlong Li, Eloise G. Lloyd, Priscilla Cheng, Giulia Biffi. An EGFR-activated subset of myofibroblastic cancer-associated fibroblasts supports local metastatic dissemination in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C039.
Abstract A056: Epithelial hyaluronan synthase 2 expression promotes pancreas cancer metastasis
Authors: Bo Tu, Heather Wright T. Wright, Christopher C. Dufort, Martin C. Whittle, Libing Feng, Shelley M. Thorsen, Sunil R. Hingorani
Journal: Cancer Research (2022)

Abstract A defining characteristic of pancreatic ductal adenocarcinoma (PDA) is its robust desmoplastic reaction that promotes tumor progression and protects PDA from treatment. As a major component of the extreme microenvironment, hyaluronan (HA) is synthesized by the hyaluronan synthase (Has) family of enzymes and secreted in excess by both epithelial cells and cancer-associated fibroblasts (CAFs). We have previously described the role of HA in binding water and swelling to create vessel-crushing interstitial gel-fluid pressures and its function as a biophysical barrier. However, HA also acts by signaling through a wide range of specific receptors that can drive proliferation, migration and invasion. In an effort to understand the role of HA in PDA development and pathogenesis, we developed a KPC mouse model of autochthonous pancreas cancer in which Has2 is conditionally deleted in tumor epithelial cells (TECs). We demonstrate that Has2-deficient epithelial cells produce little to no HA and altered the dense microenvironment. We also found that deletion of Has2 leads to an increase in overall survival and a striking reduction in metastasis. We have further investigated the cell autonomous functions of Has2, associated with 3D invasion and activation of oncogenic signaling pathways in TECs. These data implicate a potential Achilles’ heel in PDA, whereby HAS2 is required to maintain a highly metastatic phenotype involving both non-cell and cell autonomous mechanisms. Citation Format: Bo Tu, Heather Wright T. Wright, Christopher C. Dufort, Martin C. Whittle, Libing Feng, Shelley M. Thorsen, Sunil R. Hingorani. Epithelial hyaluronan synthase 2 expression promotes pancreas cancer metastasis [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A056.
Abstract A076: Somatic deletion of Tert inhibits clonal expansion of pancreatic acinar cell stem cells
Authors: Patrick Neuhöfer, Stewart J. Kim, Gregory W. Charville, Steven E. Artandi
Journal: Cancer Research (2022)

Abstract Tert-expressing cells have been identified within the acinar cell compartment of the pancreas in mice. Lineage tracing experiments indicate that these cells can maintain the exocrine compartment during homeostasis and repopulate the tissue during regeneration. Additional expression of mutant Kras in Tert-expressing acinar cells accelerates acinar clone formation and causes transdifferentiation to pre-invasive pancreatic intraepithelial neoplasms after injury. Here, using a genetic approach, we generated mice where tamoxifen injection leads to simultaneous deletion of TERT in Tert-expressing cells and activation of a reporter allele. We performed lineage tracing experiments to investigate the role of TERT in those cells. We studied the effect of acute deletion of TERT during homeostasis, regeneration and tumorigenesis. Acute deletion of TERT significantly inhibited the clone forming capability of Tert-expressing cells during homeostasis in pancreas after one year. To explore the requirement for TERT in an injury setting, we treated mice with cerulein to induce pancreatitis. Somatic inactivagion of TERT in Tert-expressing acinar stem cells impaired clone formation in mice treated with cerulein. To understand if loss of TERT affected transformation, we deleted TERT in acinar stem cells while specifically expressing activated Kras in these cells. Acute deletion of TERT in the presence of a mutant KrasG12D allele decreased the formation of metaplastic areas and PanIN lesions post-injury. These data suggest that a functional allele of Tert is necessary for the clone forming ability of Tert-expressing cells during homeostasis and regeneration as well as acinar to ductal metaplasia and PanIN formation in tumorigenesis. Citation Format: Patrick Neuhöfer, Stewart J. Kim, Gregory W. Charville, Steven E. Artandi. Somatic deletion of Tert inhibits clonal expansion of pancreatic acinar cell stem cells [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A076.
Abstract A075: NCOA4-mediated ferritinophagy is a pancreatic cancer dependency via maintenance of iron bioavailability for iron-sulfur cluster proteins
Authors: Naiara Santana-Codina, Huan Zhang, Maria Quiles del Rey, Kevin S. Kapner, Ajami Gikandi, Callum Malcolm, Clara Poupault, Miljan Kuljanin, Kristen John, Douglas E. Biancur, Brandon Chen, Nupur Das, Kristen Lowder, Connor J. Hennessey, Wesley Huang, Annan Yang, Yatrik M. Shah, Jonathan A. Nowak, Andrew J. Aguirre, Joseph D. Mancias
Journal: Cancer Research (2022)

Abstract Pancreatic ductal adenocarcinomas (PDAC) depend on autophagy for survival; however, the metabolic substrates that autophagy provides to drive PDAC progression are unclear. Ferritin, the cellular iron storage complex, is targeted for lysosomal degradation (ferritinophagy) by the selective autophagy adaptor Nuclear receptor coactivator 4 (NCOA4), resulting in release of iron for cellular utilization. Using patient-derived and genetically engineered murine models of PDAC we now demonstrate that ferritinophagy is upregulated in PDAC to sustain iron availability thereby promoting tumor progression. Mass spectrometry-based quantitative proteomics reveals that ferritinophagy fuels iron-sulfur cluster protein synthesis to support mitochondrial homeostasis. Targeting NCOA4 leads to tumor growth delay and prolonged survival but with development of compensatory iron acquisition pathways. Finally, enhanced ferritinophagy accelerates PDAC tumorigenesis, and an elevated ferritinophagy expression signature predicts for poor prognosis in PDAC patients. Together, our data reveal that maintenance of iron homeostasis is a critical function of PDAC autophagy, and we define NCOA4-mediated ferritinophagy as a therapeutic target in PDAC. Citation Format: Naiara Santana-Codina, Huan Zhang, Maria Quiles del Rey, Kevin S. Kapner, Ajami Gikandi, Callum Malcolm, Clara Poupault, Miljan Kuljanin, Kristen John, Douglas E. Biancur, Brandon Chen, Nupur Das, Kristen Lowder, Connor J. Hennessey, Wesley Huang, Annan Yang, Yatrik M. Shah, Jonathan A. Nowak, Andrew J. Aguirre, Joseph D. Mancias. NCOA4-mediated ferritinophagy is a pancreatic cancer dependency via maintenance of iron bioavailability for iron-sulfur cluster proteins [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A075.
Abstract C009: Disruption of tumor-promoting desmoplasia by adoptive transfer of fibroblast activation protein targeted chimeric antigen receptor (CAR) T cells enhances anti-tumor immunity and immunotherapy
Authors: Zebin Xiao, Leslie A. Hopper, Meghan C. Kopp, Emily McMillan, Yue Li, Richard L Barrett, Ellen Puré
Journal: Cancer Research (2022)

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease due to the poor response to current therapeutic treatments. A major barrier to effective treatment of PDAC is the extensive remodeling of tumor stroma characterized by accumulation of cancer associated fibroblasts (CAFs) and extracellular matrix which forms a physical barrier that limits access of the drugs to the cancer cells, suppresses the immune system, and attenuates efficacy of immunotherapies. Fibroblast activation protein (FAP) is highly expressed in a pro-tumorigenic subset of CAFs in PDAC. We hypothesized that depletion of FAP+-CAFs would deplete extracellular matrix (ECM) and reduce the immune suppressive function of the stroma and thereby enhance the efficacy of tumor antigen targeted CAR T cell therapy in PDAC. Using real-time tumor fragment-based 2-photon microscopy, multiparametric flow cytometry and multiplexed immunofluorescence staining, we showed that FAP targeted CAR T cells (FAP-CAR T) efficiently traffic into tumors compared with tumor-antigen (mesothelin) targeted CAR (Meso-CAR) T cells which were trapped in the stroma-rich or matrix-dense areas and led to depletion of immunosuppressive FAP+ cells and reprogrammed the fibrillar collagen network surrounding tumor nests, advancing the infiltration of FAP-CAR T cells into tumor nests. Strikingly, FAP-CAR T cell-mediated depletion for FAP+ cells also rendered the tumor microenvironment permissive to the infiltration and anti-tumor activity of tumor antigen meso-CAR T cells. Moreover, ablation of FAP+ cells markedly enhanced endogenous T cell infiltration which further enhanced anti-tumor immunity and immunotherapy in PDAC models. Thus, our findings established that FAP-CAR T cell-mediated ablation of immunosuppressive FAP+-CAFs and disruption of the desmoplastic stroma they generate, can enhance accumulation and functionality of endogenous anti-tumor immunity and CAR-T cell therapy in the context of highly desmoplastic solid tumors. Citation Format: Zebin Xiao, Leslie A. Hopper, Meghan C. Kopp, Emily McMillan, Yue Li, Richard L Barrett, Ellen Puré. Disruption of tumor-promoting desmoplasia by adoptive transfer of fibroblast activation protein targeted chimeric antigen receptor (CAR) T cells enhances anti-tumor immunity and immunotherapy [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C009.
Abstract B042: Inhibition of CPSF3 attenuates pancreatic cancer cell proliferation through disruption of histone processing
Authors: Abdulrahman A. Alahmari, Aditi Chaubey, Arwen Tisdale, Carla Schwarz, Abigail Cornwell, Kathryn Maraszek, Emily Paterson, Minsuh Kim, Swati Venkat, Eduardo Cortes Gomez, Jianmin Wang, Katerina Gurova, Michael E. Feigin
Journal: Cancer Research (2022)

Abstract Treatment regimens of pancreatic ductal adenocarcinoma (PDAC) are limited and minimally effective which potentiates the importance of discovering novel potential drug targets. We discovered widespread dysregulation of alternative polyadenylation (APA) in PDAC patients. APA is a pre-mRNA processing mechanism that generates mRNAs isoforms with distinct 3’ untranslated regions (3’UTRs). These isoforms contribute to the expression and function of mRNAs and proteins. Our recent study revealed that APA alterations in PDAC drive dysregulation of PDAC-promoting genes and present a reliable prognostic marker. APA is controlled by a suite of genes, including cleavage and polyadenylation specificity factor 3 (CPSF3). Because CPSF3 is the endonuclease that catalyzes mRNA cleavage, we here sought to target CPSF3 in PDAC. We show that CPSF3 expression is significantly upregulated and associated with unfavorable prognosis in PDAC patients. Loss of CPSF3 decreases PDAC cell proliferation, clonogenicity and tumor growth. We show that CPSF3 loss causes APA changes of tumor-associated genes and validate the tumor suppressing activity of one APA-altered gene, FHL1. Using JTE-607, a chemical inhibitor of CPSF3, we find that PDAC cells are preferentially sensitive while non-transformed cell lines are resistant to CPSF3 inhibition. Notably, we show that JTE-607 decreases proliferation-dependent histone expression and disrupts nucleosome assembly. Finally, we find that JTE-607 arrests cells in early to mid S-phase of the cell cycle, resembling histone defect-induced cell cycle arrest. Overall, we reveal alternative polyadenylation and histone processing as two distinct mechanisms underlying CPSF3-induced attenuation of cell proliferation and identify CPSF3 as a potential therapeutic target in PDAC. Citation Format: Abdulrahman A. Alahmari, Aditi Chaubey, Arwen Tisdale, Carla Schwarz, Abigail Cornwell, Kathryn Maraszek, Emily Paterson, Minsuh Kim, Swati Venkat, Eduardo Cortes Gomez, Jianmin Wang, Katerina Gurova, Michael E. Feigin. Inhibition of CPSF3 attenuates pancreatic cancer cell proliferation through disruption of histone processing [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B042.